This invention relates to a magnetic recording medium, and more particularly to a "coated type" magnetic recording medium which has a magnetic layer (and optionally a back coating) formed on a nonmagnetic support.
A magnetic recording medium, and particularly video tape, should meet the following four requirements:
(1) good picture quality (i.e., a high signal/noise (S/N) ratio measured by IEC (International Electro-technical Commission) No. 60 60B); PA1 (2) repeated use does not reduce the picture quality (i.e., the reduction of S/N ratio due to repeated tape use should be minimal); PA1 (3) wear of video head by tape is minimal (since video tape must be used repeatedly, the wear of an expensive video head damages the video-tape recorder (VTR)); and PA1 (4) the tape has a capability for cleaning the video head (i.e., the image disappears due to a tape flaw or video head gap clogging if foreign matter on the VTR video head remains unremoved. To prevent such a problem the video tape desirably has a good capability for cleaning the head by removing any foreign matter from the head as soon as it is deposited on the head).
Various methods have been proposed to meet requirements (1) to (4), but none of them has been so effective as to completely satisfy all requirements. Therefore, further improvements in magnetic recording materials are desired.